Our laboratory has pioneered the applications of silacyclopropanes in organic synthesis, and we have demonstrated that their reactions are stereospecific, stereoselective, and regioselective, but we still lacked a mild method for their synthesis. During the last funding period we developed a method for catalyzing the transfer of the silylene unit t-Bu2Si to alkenes at low temperatures. This reaction allows for the synthesis of chiral, functionalized silacyclopropanes and silacyclopropenes that had been impossible to prepare previously. This proposal describes metal-catalyzed silylene transfer to a broad range of reactive functional groups. Preliminary experimentssuggest that new paradigms for the reactions of silylene intermediatesand applications of these reactions to stereoselective synthesis are possible. During the funding period, we will address the following important issues in silylene transfer chemistry: (1) We will prepare highly functionalized three-membered ring silicon compounds, and we will explore their reactions as new methods for stereoselective synthesis. (2) We will examine silylene transfer to new functional groups, and we will use these reactions as methods to access synthetically useful functional groups. (3) We will examine the development of new, more easily functionalized group on silicon, and we will explore new methods for silylene transfer. This proposal will have considerable implications for public health. The ability to convert simple organic compounds to complex products in a single operation is a powerful approach to making new chemicals. These new methodologies may be useful to chemists in the pharmaceutical industry, who require new ways to make pharmaceutical agents more efficiently.